Celestron CGEM II 800 Schmidt-Cassegrain Telescopes CGEM II EQ Mount Manual 5l - Page 25

Polar Aligning the Mount Latitude Scales The easiest way to polar align a telescope is with a latitude scale. Unlike other methods that require you to find the celestial pole by identifying certain stars near it, this method works off of a known constant to determine how high the polar axis should be pointed. The CGEM II mount can be adjusted from 15 to 70 degrees. The constant, mentioned above, is a relationship between your latitude and the angular distance the celestial pole is above the northern (or southern) horizon; the angular distance from the northern horizon to the north celestial pole is always equal to your latitude. To illustrate this, imagine that you are standing on the North Pole, latitude +90°. The north celestial pole, which has a declination of +90°, would be directly overhead (i.e., 90° above the horizon). Now, let's say that you move one degree south - your latitude is now +89° and the celestial pole is no longer directly overhead. It has moved one degree closer toward the northern horizon. This means the pole is now 89° above the northern horizon. If you move one degree further south, the same thing happens again. You would have to travel 70 miles north or south to change your latitude by one degree. As you can see from this example, the distance from the northern horizon to the celestial pole is always equal to your latitude. NOT put you directly on the pole, it will limit the number of corrections you will make when tracking an object. It will also be accurate enough for short exposure prime focus planetary imaging (a couple of seconds) and short exposure piggyback astroimaging (a couple of minutes). Polar Align using the Hand Control The CGEM II mount has a polar alignment function called "All-Star" Polar Alignment that will help you polar align your telescope for increased tracking precision and for astroimaging. This feature allows you to choose any bright alignment star to assist in accurately aligning your telescope's mount with the North Celestial Pole. Before using the Polar Align feature, the scope must first be roughly pointed towards north and should be aligned with three stars in the sky. See the "Latitude Scale" section for help with finding north and adjusting the mounts latitude. Once your telescope is aligned on two stars and at least one additional calibration star, slew the telescope to any bright star in its Named Star database list. For best results, choose a polar alignment star that is high in the sky and near the Meridian. Try to avoid stars that are close to the west/ east horizon, directly overhead or too near the celestial pole. Once completed, press the Align button and use the Up/ Down buttons on the hand controller to select Polar Align from the list. Align Mount - After performing a two star alignment with one calibration star and slewing your telescope to any bright star in the telescope's database, select the "Align Mount" option. The telescope will then slew away from and then back to the same star. If you are observing from Los Angeles, which has latitude of 34°, then the celestial pole is 34° above the northern horizon. All a latitude scale does then is to point the polar axis of the telescope at the right elevation above the northern (or southern) horizon. To align your telescope: 1. M ake sure the polar axis of the mount is pointing due north. Use a landmark that you know faces north. 2. L evel the tripod. There is a bubble level built into the mount for this purpose. 3. Adjust the mount in altitude until the latitude indicator points to your latitude. Moving the mount affects the angle the polar axis is pointing. For specific information on adjusting the equatorial mount, please see the section "Adjusting the Mount." 1. The hand control will ask you to re-center the star in the finderscope and press ENTER. 2. The hand control will ask you to accurately center the star in your eyepiece and press ALIGN. The telescope will then "sync" on this star and slew to the position that the star should be if it were accurately polar aligned. Note: For the most accurate alignment, it is best to use a reticle eyepiece or a high power eyepiece to precisely center the star in the field of view. 3. Use the mount's latitude and azimuth adjustments to place the star in the center of the eyepiece. Do not use the direction buttons on the hand control to position the star. Once the star is centered in the eyepiece, press ENTER; the polar axis should now be pointed towards the North Celestial Pole. This method can be done in daylight, thus eliminating the need to attempt in the dark. Although this method does ENGLISH | 25